I'm also a 19 y/o university student and I pretty much feel the same way as you. My main problem is that I hate my major, so next semester I'm transferring to a major that I actually enjoy. Perhaps the reason for your frustration is that you have no passion for what you're studying.

I have to continue with my major this semester but I dropped two physics courses because I couldn't cope. I'm left with one physics course and I understand how it feels to be anxious around exam time. My advice is to get a study buddy, someone who's not necessarily a close friend but who is smart enough and nice enough to spend time with you answering your questions and helping you study. That's what I'm doing and it's making my situation more bearable.

Good luck